Every four years, it seems, especially among Democrats, the idea that the youth vote will rise up and make a difference gets bandied about excitedly and then … well, not much happens. Young people were supposed to put Al Gore over the top in 2000; four years later, they were supposed to deliver the Democratic nomination to Howard Dean. This year, the youth excitement has attached itself to Barack Obama. But unlike in the past, there’s reason to expect that this enthusiasm might produce real results.

In past cycles, anecdotal evidence of increased youth involvement—the media’s fixation on “Rock the Vote,” say, or on Howard Dean’s Internet supporters—never translated to the polls: no tidal wave of young voters ever materialized. But for Obama, one has. Take Iowa: In 2000, Democratic caucus voters younger than 30 made up about 9 percent of the electorate. In the 2008 Democratic caucus, they made up nearly a quarter. If Obama can replicate that turnout in a general election, he’ll have a very good shot at becoming president.

The “Reagan coalition” is dead.

We’ll see. But it sure looks as if the Reagan coalition—the combination of economic, foreign-policy, religious, and cultural conservatives that helped carry Ronald Reagan and every subsequent Republican president to victory—is on its last legs. Tensions within the movement over the Iraq War, the influence of evangelicals, the wisdom of supply-side economics, and other issues are severely compressing the arteries of the modern conservative movement. George Allen, the senator from Virginia who was a front-runner for the Republican nomination, sought to claim the coalition’s support, but his famous “macaca” comment, immortalized on YouTube, cost him reelection to the Senate and snuffed his presidential hopes. Mitt Romney was the next to campaign as “the Reagan candidate,” during the 2008 Republican primaries, but to no avail.

Among Republicans, genuflecting to Reagan has become as obligatory as expounding on one’s opposition to abortion, on “judges who legislate from the bench,” and on other inviolable positions that any serious conservative candidate must take. At most, these vows solidify a dwindling base; they do nothing to expand it. John McCain is the exception that proves the nostrum: he was closer to Reagan than any of the other candidates and exemplifies the martial values that the coalition holds dear. And yet, for thinking independently, he was an outcast. Demographically, it’s hard to sustain a political coalition with only the votes of white men; pragmatically, Reagan’s ideas seem less suited to a 21st-century world. McCain will likely draw weak support among economic, religious, and cultural conservatives. If he wins, it will probably be because he was able to attract key groups—Latinos, Jews, and blue-collar white women—in bigger numbers than Reagan did.

Both Obama and McCain can “expand the map.”

Yes. Heck, they might as well play cartographer. If you follow politics at all, the infamous red-and-blue electoral map showing the results from the 2004 election is probably burnt onto your retinas. Get new retinas. The following states will be competitive in 2008: Colorado, Virginia, Missouri, even North Carolina, Connecticut, and Oregon. Both McCain and Obama supporters believe their candidate’s personal appeal will make him competitive in states where other members of their party wouldn’t have had a chance.

Neither candidate is yet identified with the extremes of his party, and both have historically demonstrated a propensity (though lately, a diminishing one) to attract independents, and even voters from the other party. McCain excelled in “blue” states like New Hampshire. And Obama, owing partly to his message of “post-partisanship” and partly to his race, ran strongly in “red” states like North Carolina and Georgia (whose large black populations voted for him overwhelmingly). The practical need to become the faces of the Democratic and Republican parties will necessarily limit each candidate’s crossover appeal, but it is a limitation that Obama, in particular, by having the ability to spend massive sums of money, might be able to overcome.